Polishing pad, chemical mechanical polishing apparatus and method for manufacturing polishing pad

ABSTRACT

A polishing pad with reduced cost and easy manufacturability without waste is provided. A disc-shaped polishing layer  31  having a plurality of through holes  34  formed therein, an adhesive layer  33  provided only in a position in a back surface of the polishing layer  31  where no through hole  34  is formed and a disc-shaped support plate  32  having a flat surface, which is joined to the back surface of the polishing layer  31  by the adhesive layer  33  are provided. Since an adhesive layer  33  is not exposed to bottoms of the through holes  34  of the polishing layer  31 , acting the slurry over the adhesive layer  33  to strip the polishing layer  31  from the support plate  32  is inhibited. Since the through holes  34  formed in the polishing layer  31  do not extend to the support plate  32 , a decrease in the mechanical strength is not caused.

This application is based on Japanese patent application No.2006-85,312, the content of which is incorporated hereinto by reference.

BACKGROUND

1. Technical Field

The present invention relates to a polishing pad utilized in a chemicalmechanical polishing (CMP) process, and particularly relates to apolishing pad having a multiple-layered structure, in which a supportplate is joined to a polishing layer having a plurality of through holesformed therein, a CMP apparatus having such polishing pad and a methodfor manufacturing such polishing pad.

2. Related Art

Currently, in processes for manufacturing semiconductor devices, achemical mechanical polishing (CMP) process may be often performed forproviding finer planarized surfaces. In such CMP process, a disc-shapedpolishing pad is supported by a shaft, and is driven to be rotated,while a slurry is supplied to such polishing pad that is driven to berotated. A workpiece is compressing-contacted with the surface of thepolishing pad in such condition to planarize the surface of theworkpiece.

Better retaining-ability of a slurry is required for the polishing padutilized in such CMP process. Thus, as shown in FIG. 4 and FIG. 5, anapproach of providing a polishing pad 10 having a multiple-layeredstructure of a support plate 12 and a polishing layer 11, surface ofwhich is provided with a large number of through holes 13 formedtherein. In such polishing pad 10, the polishing layer 11 is joined tothe support plate 12 by an adhesive layer 14.

Here, a first conventional example of a method for manufacturing apolishing pad 10 is described as follows in reference to FIGS. 6A to 6D.First of all, a disc-shaped polishing layer 11 is prepared as shown inFIG. 6A, and through holes 13 are formed in such polishing layer 11 by apunching processing as shown in FIG. 6B.

Then, as shown in FIG. 6C, a disc-shaped support plate 12 is prepared,and an adhesive layer 14 is provided over the surface thereof. Theadhesive layer 14 may be formed by, for example, an application of anadhesive agent, or pasting tapes on both sides thereof. Then, as shownin FIG. 6D, a back surface of the polishing layer 11 is joined to asurface of the support plate 12 by the adhesive layer 14 to provide afinished product of the polishing pad 10 (see, for example, JapanesePatent Laid-Open No. H09-117,855 (1997)).

In addition, a second conventional example of a method for manufacturinga polishing pad is described as follows in reference to FIGS. 7A to 7D.First of all, a disc-shaped polishing layer 21 is prepared as shown inFIG. 7A, and a disc-shaped support plate 22 is prepared, as shown inFIG. 7B.

Next, as shown in FIG. 7C, the polishing layer 21 is joined to thesupport plate 22 by an adhesive layer 24. Then, as shown in FIG. 7D,through holes 23 extending through the polishing layer 21 from thesurface thereof are formed to provide a finished product of thepolishing pad 20 (see, for example, Japanese Patent Laid-Open No.H11-156,699 (1999)).

In addition to above, through holes 13 and 23 of the polishing layer 11and 21 as described above may be formed as circular small holes as shownin FIG. 4, or may be formed as linear concave trenches (not shown).

In the polishing pad 10 produced by the above described first method formanufacturing the polishing pad, as shown in FIG. 5 and FIG. 6D, anadhesive layer 14 is partially exposed in the bottom of the throughholes 13. Thus, the slurry acts on the adhesive layer 14 and degradesthe adhesive strength such that the polishing layer 11 is easily flakedoff from the support plate 12. Further, if the flaked adhesive layer 14is mixed into the slurry, a failure is caused in the workpiece.

On the other hand, in the polishing pad 20 produced by theabove-described second method for manufacturing the polishing pad, it isdifficult to form the through holes 23 only in the polishing layer 21.Thus, as shown in FIG. 7D, the through holes 23 are necessarily formedso as to reach to the support plate 22, providing a deterioratedmechanical strength of the polishing pad 20.

In addition, as shown in FIG. 7C, through holes 23 are not yet formed atthe time the support plate 22 is joined to the polishing layer 21. Thus,it is impossible to eliminate air trapped in the adhesive layer 24through the through hole 23 while joining the polishing layer 21 to thesupport plate 22. This leads joining the polishing layer 21 to thesupport plate 22 while air is remained in the adhesive layer 24,providing a reduced bonding strength.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided apolishing pad having a multiple-layered structure and being utilized ina chemical mechanical polishing (CMP) process, comprising: a disc-shapedpolishing layer having a plurality of through holes formed to extendfrom a front surface to a back surface thereof; an adhesive layerprovided only in a position in a back surface of the polishing layerwhere the through hole is not formed; and a disc-shaped support platehaving a flat surface, which is joined to the back surface of thepolishing layer by the adhesive layer.

Since an adhesive layer is not exposed to the bottoms of the throughholes of the polishing layer, the degradation of the adhesive strengthby the slurry is inhibited. And since the through holes formed in thepolishing layer do not extend to the support plate, a decrease in themechanical strength is not caused.

According to another aspect of the present invention, there is provideda chemical mechanical polishing (CMP) apparatus for performing a CMPprocess applied to a workpiece utilizing a polishing pad, comprising: apolishing pad according to the present invention; a disc-shaped platenhaving a front surface, which is joined to a back surface of thepolishing pad; a pad actuating unit for rotating the polishing padjoined on the platen; a slurry supplying unit for supplying a slurry tothe polishing pad that is actuated to be rotated; and a workpiecepressing unit for supporting the workpiece and pressing the workpiece tothe polishing pad that is actuated to be rotated. Thus, since the CMPapparatus of the present invention is capable of polishing a workpieceutilizing the polishing pad according to the present invention, actingthe slurry over the adhesive layer of the polishing pad and thedegradation of the adhesive strength by the slurry is inhibited.

According to further aspect of the present invention, there is provideda method for manufacturing a polishing pad, which is utilized in achemical mechanical polishing (CMP) process, including: providing anadhesive layer and a stripping form on a back surface of a disc-shapedpolishing layer having a front surface serving as a polishing surface;forming a plurality of through holes, which extend from a surface of thepolishing layer through the adhesive layer to a back surface of thestripping form; stripping the stripping form from the back surface ofthe polishing layer having the plurality of through holes formedtherein; and joining the back surface of the polishing layer exposed bystripping the stripping form to a surface of a support plate by theadhesive layer.

Since the polishing pad is produced to have a structure that preventsexposing the adhesive layer in the bottoms of the through holes of thepolishing layer in the method for manufacturing the polishing pad of thepresent invention, the polishing pad that prevents acting the slurryover the adhesive layer of the polishing pad is produced, and since thethrough holes formed in the polishing layer do not reach to the supportplate, the polishing pad having an improved mechanical strength isproduced.

In addition to above, the term “flat surface” appeared in claims and thedescription of the present invention means a surface that is physicallyformed for the aim of creating a flat surface, and of course it isnecessary to be a geometric completely flat plane.

Since an adhesive layer is not exposed to bottoms of through holes ofthe polishing layer, acting the slurry over the adhesive layer and thedegradation of the adhesive strength by the slurry is inhibited, so thata peeling off of the polishing layer from the support plate can beprevented. And since through holes formed in the polishing layer do notextend to the support plate, a decrease in the mechanical strength isprevented, so that an improved polishing of the workpiece can bepresented.

Since the CMP apparatus of the present invention is capable of polishinga workpiece utilizing the polishing pad according to the presentinvention, acting the slurry over the adhesive layer of the polishingpad and the degradation of the adhesive strength by the slurry isinhibited, so that an improved polishing of the workpiece can bepresented without causing a peeling off of the polishing layer from thesupport plate.

Since the polishing pad can be produced to have a structure thatprevents exposing the adhesive layer in the bottoms of the through holesof the polishing layer in the method for manufacturing the polishing padof the present invention, there can produce the polishing pad thatprevents acting the slurry over the adhesive layer of the polishing padand the degradation of the adhesive strength by the slurry. And sincethe through holes formed in the polishing layer do not reach to thesupport plate, the polishing pad having an improved mechanical strengthcan be produced.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, advantages and features of the presentinvention will be more apparent from the following description taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a schematic vertical cross-sectional view, showing a structureof a main part of a polishing pad in an embodiment of the presentinvention;

FIGS. 2A to 2E are a schematic vertical cross-sectional views,illustrating operations of a method for manufacturing the polishing padaccording to the present invention;

FIG. 3A is a schematic side view, showing a condition of mounting apolishing pad of the present embodiment onto a platen of a CMPapparatus, and FIG. 3B is a schematic side view, showing a condition ofmounting a conventional polishing pad onto a platen of a CMP apparatus;

FIG. 4 is a plan view, showing an appearance of a conventional polishingpad;

FIG. 5 is a schematic vertical cross-section view, showing a structureof a main part of a conventional polishing pad;

FIGS. 6A to 6D are vertical cross-section views, illustrating operationsof a first conventional method for manufacturing a conventionalpolishing pad; and

FIGS. 7A to 7D are vertical cross-section views, illustrating operationsof a second conventional method for manufacturing a conventionalpolishing pad.

DETAILED DESCRIPTION

The invention will be now described herein with reference toillustrative embodiments. Those skilled in the art will recognize thatmany alternative embodiments can be accomplished using the teachings ofthe present invention and that the invention is not limited to theembodiments illustrated for explanatory purposed.

Preferable embodiments of the present invention will be described asfollows in further detail, in reference to FIG. 1, FIGS. 2A to 2E andFIGS. 3A and 3B. In all figures, identical numeral is assigned to anelement commonly appeared in both of the description of the presentinvention the description of the related art, and the detaileddescription thereof will not be repeated.

A polishing pad 30 of the present embodiment is formed to have adual-layer structure, which is one of typical multiple-layeredstructure. Thus, as shown in FIG. 1, a disc-shaped support plate 32 isjoined to a disc-shaped polishing layer 31 by an adhesive layer 33.

A plurality of through holes 34 composed of circular small holes areformed to extend from a front surface to a back surface of the polishinglayer 31. The adhesive layer 33 is provided on the back surface of thepolishing layer 31 only in a position where no through hole 34 isformed.

Now, a method for manufacturing the polishing pad 30 of the presentembodiment will be described in reference to FIGS. 2A to 2E. First ofall, the disc-shaped polishing layer 31 is prepared as shown in FIG. 2A,and the adhesive layer 33 and a stripping form 36 are provided on theback surface thereof as shown in FIG. 2B.

More specifically, a two-sided tape (not shown) having the adhesivelayer 33, which is provided with stripping forms 36 affixed on bothsides thereof, is prepared. Only a stripping form 36 in the side of thefront surface of the two-sided tape is stripped to expose the adhesivelayer 33.

The front surface of such adhesive layer 33 is pasted on the backsurface of the polishing layer 31, so that the adhesive layer 33 and thestripping form 36 are provided on the polishing layer 31. In suchcondition, as shown in FIG. 2C, a plurality of through holes 34 areformed in the polishing layer 31, the adhesive layer 33 and thestripping form 36.

In next, as shown in FIG. 2D, the stripping form 36 is stripped from theback surface of the polishing layer 31, which is provided with aplurality of through holes 34 formed therein. Then, as shown in FIG. 2E,a front surface of the support plate 32 is joined to the back surface ofpolishing layer 31 exposed by stripping the stripping form 36 by theadhesive layer 33 to complete the manufacture of the polishing pad 30.

The polishing pad 30 produced by the method for manufacturing thepolishing pad as described above is utilized in a CMP process forworkpieces as a part of the CMP apparatus 40, as shown in FIG. 3A. SuchCMP apparatus 40 includes, for example, a platen 41, a pad actuatingunit 42, a slurry supplying unit 43, a workpiece pressing unit (notshown) and the like.

The platen 41 is formed to have a disc-shape, which is the same as thetwo-dimensional geometry of the polishing pad 30. The polishing pad 30is mounted in a replaceable manner on the front surface of the platen 41by an adhesive agent or a two-sided tape. The pad actuating unit 42actuates a rotation of the platen 41 to rotate the polishing pad 30 thatis joined on the surface thereof.

The slurry supplying unit 43 supplies a slurry S to the rotatingpolishing pad 30. The workpiece pressing unit functions as supportingthe workpiece and compressing-contacting thereof with the rotatingpolishing pad 30. In the CMP apparatus 40 having such structure, theworkpiece can be CMP processed utilizing the polishing pad 30.

In the polishing pad 30 produced by the method for manufacturing thepolishing pad of the present embodiment, as shown in FIG. 2E and FIG. 1,an exposure of the adhesive layer 33 in the bottoms of the through holes34 is prevented. Thus, unwanted peeling-off of the polishing layer 31from the support plate 32 due to acting of the slurry S over theadhesive layer 33 can be sufficiently prevented.

Further, a failure of a workpiece due to a contamination of the flakedadhesive layer 33 into the slurry S can be sufficiently prevented. Inaddition, since the through holes 34 are not formed to extend to thesupport plate 32, a decrease in the mechanical strength thereof can alsobe prevented.

Moreover, in the method for manufacturing the polishing pad according tothe present embodiment, as shown in FIG. 2C to FIG. 2E, the throughholes 34 are formed at the time when the polishing layer 31 is joiningto the support plate 32. Air trapped in the adhesive layer 33 can beremoved via the through holes 34, while the polishing layer 31 isjoining to the support plate 32. Therefore, the polishing layer 31 canbe joined to the support plate 32 without remained air in the adhesivelayer 33, thereby ensuring an improved bonding strength therebetween.

In addition, in the method for manufacturing the polishing pad of thepresent embodiment, the through holes 34 are formed, after the adhesivelayer 33 and the stripping form 36 on the back surface of the polishinglayer 31 are provided, as described above. Thus, handling of thepolishing layer 31 having the adhesive layer 33 provided thereon isfacilitated. In addition, a contamination of the adhesive layer 33 isavoided.

Therefore, the polishing pad 30 containing no defect in the adhesivelayer 33 can be easily manufactured.

Japanese Patent Laid-Open No. 2001-219,362 discloses a structure of apolishing pad 50 having a single layer structure and a technique forjoining the polishing pad 50 to a platen 41, as shown in FIG. 3B. Thepolishing pad 50 includes a plurality of through holes 51 formed toextend from a front surface to a back surface thereof.

More specifically, in the polishing pad 50, an adhesive layer 52 isprovided on the back surface only in a position where no through hole 51is formed. Such polishing pad 50, in turn, is joined to the platen 41 bythe adhesive layer 52.

However, this is the technique for joining the polishing pad 50 of thesingle layer structure to the platen 41, and it is difficult to simplyapply such technique for the single layer structure to the technique forjoining the polishing layer 31 of the polishing pad 30 having themultiple-layered structure to support plate 32.

Japanese Patent Laid-Open No. 2001-219,362 also discloses that theadhesive layer 52 is formed by employing an adhesive agent or atwo-sided tape. When the adhesive layer 52 is formed by employing anadhesive agent, through holes 51 are formed in the polishing pad 50coated with an adhesive agent over the back surface thereof.

However, this leads to handling the polishing pad 50 under thecondition, in which the adhesive agent coated thereon is exposed, andthus the handling thereof is difficult and a contamination may bepossibly caused in the adhesive agent.

It is not intended that the present invention is limited to theconfigurations illustrated in the above-described embodiment, andvarious modifications thereof are available. For example, while it isassumed that the through holes 34 of the polishing layer 31 are circularsmall holes in the above-described configuration, such through holes 34may alternatively be formed to have variety of geometries (not shown)such as cross-shaped heteromorphy holes, linear concave trenches and thelike.

Further, the configuration of simultaneously providing the adhesivelayer 33 and the stripping form 36 on the polishing layer 31 by pastingthe adhesive layer 33 of the two-sided tape, in which only one strippingform in one side is stripped, on the polishing layer 31 is illustratedin the above-described configuration.

Alternatively to above, after the adhesive agent is applied on the backsurface of the polishing layer 31 to form the adhesive layer 33, thestripping form 36 may be pasted thereon. In this case, though theadhesive layer 33 is formed of an adhesive agent, easier handling ofpolishing layer 31 is provided and a contamination in the adhesive agentis avoided.

It is apparent that the present invention is not limited to the aboveembodiment, and may be modified and changed without departing from thescope and spirit of the invention.

1. A polishing pad having a multiple-layered structure and beingutilized in a chemical mechanical polishing (CMP) process, comprising: adisc-shaped polishing layer having a plurality of through holes formedto extend from a front surface to a back surface thereof; an adhesivelayer provided only in a position in a back surface of said polishinglayer where said through hole is not formed; and a disc-shaped supportplate having a flat surface, which is joined to said back surface of thepolishing layer by said adhesive layer.
 2. The polishing pad accordingto claim 1, wherein a surface of said support plate is exposed in abottom of said through hole in said polishing layer without disposingsaid adhesive layer thereon.
 3. A chemical mechanical polishing (CMP)apparatus for performing a CMP process for a workpiece with a polishingpad, comprising: the polishing pad as set forth in claim 1; adisc-shaped platen having a front surface, which is joined to a backsurface of said polishing pad; a pad actuating unit for actuating arotation of said platen that is provided with said polishing pad; aslurry supplying unit for supplying a slurry to said polishing pad thatis actuated to be rotated; and a workpiece pressing unit for supportingsaid workpiece and pressing said workpiece to said polishing pad that isactuated to be rotated.
 4. A chemical mechanical polishing (CMP)apparatus for performing a CMP process for a workpiece with a polishingpad, comprising: the polishing pad as set forth in claim 2; adisc-shaped platen having a front surface, which is joined to a backsurface of said polishing pad; a pad actuating unit for actuating arotation of said platen that is provided with said polishing pad; aslurry supplying unit for supplying a slurry to said polishing pad thatis actuated to be rotated; and a workpiece pressing unit for supportingsaid workpiece and pressing said workpiece to said polishing pad that isactuated to be rotated.
 5. A method for manufacturing a polishing pad,which has a multiple-layered structure and is utilized in a chemicalmechanical polishing (CMP) process, including: providing an adhesivelayer and a stripping form on a back surface of a disc-shaped polishinglayer having a front surface serving as a polishing surface; forming aplurality of through holes, which extend from a surface of saidpolishing layer through said adhesive layer to a back surface of saidstripping form; stripping said stripping form from the back surface ofsaid polishing layer having said plurality of through holes formedtherein; and joining the back surface of said polishing layer exposed bystripping said stripping form to a surface of a support plate by saidadhesive layer.
 6. The method for manufacturing the polishing padaccording to claim 5, further comprising preparing a two-sided tapehaving a structure including an adhesive layer and stripping formsaffixed to both sides of the adhesive layer, wherein said providing theadhesive layer and the stripping form on the back surface of thedisc-shaped polishing layer includes providing an exposed adhesive layerof said two-sided tape onto a back surface of the polishing layer, saidexposed adhesive layer of the two-sided tape being exposed by strippingonly said stripping form disposed on the front surface of said two-sidedtape.
 7. The method for manufacturing the polishing pad according toclaim 5, wherein said providing the adhesive layer and the strippingform on the back surface of the disc-shaped polishing layer includespasting said stripping form after said adhesive layer is provided withthe back surface of said polishing layer by an application of anadhesive agent.